NAME

SYNOPSIS

DESCRIPTION

The y0(), y1(), and yn() functions shall compute Bessel functions of x of the second kind of orders
0, 1, and n, respectively.

An application wishing to check for error situations should set errno to zero and call
feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if errno is non-zero or
fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.

RETURN VALUE

Upon successful completion, these functions shall return the relevant Bessel value of x of the second kind.

If x is NaN, NaN shall be returned.

If the x argument to these functions is negative, -HUGE_VAL or NaN shall be returned, and a domain error may occur.

If x is 0.0, -HUGE_VAL shall be returned and a pole error may occur.

If the correct result would cause underflow, 0.0 shall be returned and a range error may occur.

If the correct result would cause overflow, -HUGE_VAL or 0.0 shall be returned and a range error may occur.

ERRORS

These functions may fail if:

Domain Error

The value of x is negative.

If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [EDOM]. If the
integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall be
raised.

Pole Error

The value of x is zero.

If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [ERANGE]. If the
integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the divide-by-zero floating-point exception shall be
raised.

Range Error

The correct result would cause overflow.

If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [ERANGE]. If the
integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the overflow floating-point exception shall be
raised.

Range Error

The value of x is too large in magnitude, or the correct result would cause underflow.

If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno shall be set to [ERANGE]. If the
integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, then the underflow floating-point exception shall be
raised.

The following sections are informative.

EXAMPLES

None.

APPLICATION USAGE

On error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT) are independent of
each other, but at least one of them must be non-zero.

CHANGE HISTORY

Issue 5

The DESCRIPTION is updated to indicate how an application should check for an error. This text was previously published in the
APPLICATION USAGE section.

Issue 6

The DESCRIPTION is updated to avoid use of the term "must" for application requirements.

The RETURN VALUE and ERRORS sections are reworked for alignment of the error handling with the ISO/IEC 9899:1999
standard.

IEEE Std 1003.1-2001/Cor 2-2004, item XSH/TC2/D6/148 is applied, updating the RETURN VALUE and ERRORS sections.
The changes are made for consistency with the general rules stated in "Treatment of Error Conditions for Mathematical Functions''
in the Base Definitions volume of IEEE Std 1003.1-2001.

End of informative text.

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